Design of the Marabu was started in July 1960 and construction of the prototype began in the following September of the same year. Fitted with an 150 hp Lycoming O-320 four-cylinder horizontally-opposed air-cooled engine, it flew for the first time on August 28, 1965, with Ueli Häusermann at the controls. As manufacturer is also reported Barfüss (as it still is registered) and Uetz (Markwalder was a constructor for the Flugzeugbau-Firma Uetz at Fehraltorf).
Span: 31 ft 10 in (9.70 m)
Length: 24 ft 3.25 in (7.40 m)
Height: 6 ft 6.75 in (2.00 m)
Wing area: 150.7 sq.ft (14 sq.m)
Weight empty: 1,422 lb (645 kg)
Loaded weight: 2,140 lb (970 kg)
Max speed: 171 mph (275 kmh) at sea level
Cruise speed: 152 mph (245 kmh) at sea level
Climb: 985 ft (300 m)/min."